Why is it in the News?

The Widal test's tendency to produce inaccurate results is clouding the understanding of India's typhoid burden, leading to increased costs, and exacerbating antimicrobial resistance risks.

What is the Widal Blood Test?

• A Widal test is a serological diagnostic test for typhoid fever.
• It helps evaluate the level of antibodies produced by the body in response to the Salmonella bacterial infection that causes typhoid fever in patients.
• Widal blood test is also known as a typhoid blood test report, as it is widely used for diagnosing typhoid fever.
  • The symptoms of typhoid fever may be similar to those of other diseases, which can make the diagnosis of typhoid difficult without proper testing.
• Typhoid fever is a severe illness caused by a bacterium called Salmonella Typhi.
• This bacterium affects the gastrointestinal system and causes a range of symptoms such as high fever, diarrhoea or constipation, headache, abdominal pain, fatigue, weight loss, and red spots.
• The bacteria usually enter the body through contaminated food or water.
  • Typhoid requires prompt treatment to prevent further complications such as severe intestinal perforation or bleeding.
• The Widal blood test is a quick and easy serological test that can help confirm or rule out whether a fever is due to a typhoid infection.
• Typically, typhoid symptoms appear within 6 to 30 days of exposure to the bacterial infection.
• The Widal test is designed to detect antibodies against O (somatic) and H (flagellar) antigens that cause the infection and typhoid fever.
• Infection through these antigens produces specific antibodies in response.
• The Widal blood test analyses the interaction between these two antigens and the antibodies produced in the patient's body through a blood sample.
  • Detecting the presence of these antibodies in the Widal blood test indicates a bacterial infection.
• However, it has several limitations and has been phased out in many countries due to its potential for inaccuracy.
• The World Health Organization (WHO) advises against relying heavily on the Widal Test because various factors can influence its results.
  • For example, a single positive result does not definitively confirm an active typhoid infection and a negative result does not necessarily rule it out.
• Additionally, obtaining an accurate diagnosis requires testing at least two serum samples taken 7-14 days apart, which can be time-consuming and often impractical.
• In areas with a continuous high burden of typhoid, baseline antibody levels may already be elevated, complicating the interpretation of results without knowing the appropriate cut-off values.
  • Furthermore, cross-reactivity with antibodies produced against other infections or vaccinations can lead to false positives.
  • Prior antibiotic therapy can also impact antibody levels, resulting in false negatives.
• Despite its accessibility and historical significance, the Widal Test's limitations emphasize the need for more accurate and reliable diagnostic methods for typhoid fever.

Why is it in the News?

The World Health Organization (WHO) has launched a global network of laboratories to identify and monitor potentially novel coronaviruses that could emerge shortly.

What is CoViNet?

• The Coronavirus Network (CoViNet) is a global collaboration of laboratories with expertise in human, animal, and environmental coronavirus surveillance.
  • This network aims to identify and monitor potential new coronaviruses that could emerge and impact public health worldwide.
• To enhance pandemic preparedness, CoViNet will expand its scope to include animal health and environmental surveillance, as well as timely risk assessments.
  • This will allow the World Health Organization (WHO) to develop more informed policies and protective measures against future viral outbreaks.
• CoViNet will also play a pivotal role in building and supporting laboratory capacities in low- and middle-income countries to monitor MERS-CoV and other emerging coronaviruses of public health importance.
  • By fostering knowledge exchange and capacity building, CoViNet aims to strengthen the global response to coronavirus threats.
• Furthermore, data generated through CoViNet's efforts will guide the work of the WHO's Technical Advisory Groups on Viral Evolution (TAG-VE) and Vaccine Composition (TAG-CO-VAC). These groups rely on cutting-edge research and surveillance data to inform public health policies and vaccination strategies.
• With 36 laboratories from 21 countries across all six WHO regions, CoViNet currently encompasses a wide range of expertise and resources.
  • Three Indian institutions, namely, the Council of Scientific and Industrial Research-National Environmental Engineering Research Institute, the Indian Council of Medical Research-National Institute of Virology in Pune, and the Translational Health Science and Technology Institute, proudly represent the country in this global network dedicated to coronavirus surveillance and preparedness.

About the World Health Organization (WHO):

• The World Health Organization (WHO) stands as a paramount global health authority, dedicated to promoting health, preventing diseases, and improving healthcare systems worldwide.
• Established in 1948, WHO operates as a specialized agency of the United Nations, with its headquarters in Geneva, Switzerland.
• It collaborates with governments, international organizations, and civil society to address pressing health challenges and provide guidance and support to countries in need.
• WHO's mandate encompasses a wide array of health-related issues, including infectious diseases, non-communicable diseases, mental health, maternal and child health, and environmental health.
• Through research, policy development, and technical assistance, WHO plays a vital role in shaping health policies, setting standards, and coordinating responses to health emergencies such as pandemics and natural disasters.
• With a mission to ensure the highest attainable level of health for all people, WHO continues to lead efforts in global health governance, advocacy, and capacity-building, striving for a healthier, safer, and more equitable world.

Why in the News?

The World Health Organization (WHO) has announced that Guinea's Health Ministry has officially notified them of a diphtheria outbreak.

What is Diphtheria?

• Diphtheria, an extremely contagious and infectious disease, instigates severe inflammation in the nose, throat, and trachea (windpipe).
• This ailment is caused by strains of bacteria known as Corynebacterium diphtheriae, which produce a potent toxin responsible for the onset of illness.

Causes:

• The bacterial infection spreads through various means, including respiratory droplets emitted during coughing or sneezing.
• Transmission can also occur through contact with infected open sores or ulcers. The bacteria's toxin is the primary culprit behind the illness.

Symptoms:

• Manifesting 2-5 days post-infection, symptoms of diphtheria encompass a thick, grey membrane covering the throat and tonsils, a sore throat, hoarseness, swollen glands in the neck, difficulty breathing, nasal discharge, fever, chills, and fatigue.
• If the toxin enters the bloodstream, it can lead to damage to the heart, nerves, and kidneys.

Infection and Spread:

• Diphtheria bacteria thrive on person-to-person transmission, emphasizing respiratory droplets as a common mode of contagion.
• Skin infections are possible but seldom result in severe disease.

Treatment:

• Combatting diphtheria involves a dual-pronged approach:
• Antitoxin (Anti-diphtheritic Serum): This neutralizes bacterial toxins and is specifically employed for respiratory system infections. The antitoxin acts on toxins that haven't bound with cells and tissues.
• Antibiotics (Erythromycin or Penicillin): These medications eradicate the bacteria, preventing further spread. Antibiotics are effective against both the respiratory system and skin infections caused by diphtheria.